Venous Thromboembolism Prophylaxis: Inadequate and Overprophylaxis When Comparing Perceived Versus Calculated Risk

Abstract

Guidelines for venous thromboembolism (VTE) prophylaxis recommend appropriate risk stratification using risk estimation models as high risk or low risk followed by initiation of chemical or mechanical prophylaxis, respectively. We explored adherence to guidelines on the basis of the documentation of VTE prophylaxis. A retrospective medical record review of 437 consecutive adult patients (≥18 years) admitted to general medical wards under medicine service between January 1, 2015, and March 1, 2015, was performed. The primary outcome was appropriateness of risk stratification using the Padua Prediction Score. Secondary outcomes were appropriateness of type of prophylaxis (chemical vs mechanical) and cost-benefit analysis. We observed appropriate stratification based on the documented risk (compared with the calculated risk) in 54.9% of the patients (40.8% with low risk vs 72.1% with high risk; P<.001). Overall, 182 of 240 low-risk patients received unnecessary chemical prophylaxis, whereas 23 of 197 high-risk patients without contraindications for chemical prophylaxis received mechanical or no prophylaxis. No clinical VTE events were noted in the patients inappropriately assigned to mechanical or no prophylaxis. Also, 67.3% of patients with both low documented and low calculated risk and 74.5% of patients with low documented and high calculated risk received chemical prophylaxis, consistent with a tendency toward overtreatment. A total of 4068 annualized patient-days ($77,652/y) of inappropriate chemical prophylaxis were administered. In conclusion, estimation of the risk of VTE based on clinical impression was not congruent with the risk calculated using risk prediction models and was associated with a tendency toward overtreatment. These data support the inclusion of VTE risk calculators in electronic health record systems.